This invention describes a method for synthesizing hydroxycarboxylic acid salts from polyols using nitric acid and oxygen as the oxidizing agents and applying the hydroxycarboxylic acid salts for uses that include corrosion inhibiting materials and components of concrete.
Hydroxycarboxylic acids and hydroxycarboxylic acid salts are well recognized as corrosion inhibitors particularly effective in inhibiting metal corrosion when the metal is in contact with water or an aqueous solution (U.S. Pat. No. 2,529,177; U.S. Pat. No. 2,529,178; Erasmus, 1971; Marukume, 1993; Hashimoto, 1976; and U.S. Pat. No. 4,120,655).
Nieland et al. taught that these hydroxycarboxylic acids, or salts thereof, may contain a single carboxylic acid function, as in the case of gluconic acid (U.S. Pat. No. 2,529,178), or multiple carboxylic acid functions as in the case of tartaric acid, a hydroxydicarboxylic acid, or citric acid, a hydroxytricarboxylic acid (U.S. Pat. No. 2,529,170). Nieland et al. have also taught that hydroxycarboxylic acids, or salts thereof, with multiple carboxylic acid functions, such as tartaric acid (U.S. Pat. No. 2,529,170), generally exhibit better corrosion inhibition properties than do comparable hydroxymonocarboxylic acids, such as gluconic acid (U.S. Pat. No. 2,529,178).
Hydroxycarboxylic acids have also been shown to inhibit metal corrosion in aqueous salt brine such as sea water (Mor, 1971; Mor 1976; and Wrubl, 1984) or formulated brine solutions (Kuczynski, 1979; Korzh, 1981; Sukhotin, 1982; and Abdallah, 1999), some employed for specific applications, such as in industrial cooling systems (Sukhotin, 1982).
Metal corrosion inhibitors are commonly mixtures of components that include hydroxycarboxylic acids, or salts thereof, the mixtures sometimes described as providing a synergistic or cooperative effect with components other than hydroxycarboxylic acids in corrosion inhibition rendering corrosion inhibition properties better than and/or different from the individual components.
Crambes et al. describe (U.S. Pat. No. 4,120,655) the use of hydroxycarboxylic acids selected from the group tartaric, citric and gluconic in addition to a phosphoric acid ester of an alkanolamine to inhibit the corrosion of ferrous metals in aqueous media including aqueous media with high salt content. Numerous additional examples of the use of hydroxycarboxylic acids or hydroxycarboxylic salts in mixtures with components other than hydroxycarboxylic acids that serve as corrosion inhibiting agents have been reported (U.S. Pat. Nos. 3,589,859; 3,711,246; 4,108,790; 5,891,225; 5,531,931; 5,330,683; and Foroulis, 1971; Foroulis, 1972; Foroulis, 1973; Hiroshige, 1973; and Birk, 1976).
Sufrin et al. (U.S. Pat. No. 5,330,683) claims use of gluconate, with additional components that include sorbitol or mannitol, as a corrosion inhibition agent in brine. However, it is clear from earlier reports (Mor, 1971; Mor 1976; Wrubl, 1984; and Kuczynsiki, 1979) that gluconate had been reported effective as a corrosion inhibitor in brine.
Hydroxycarboxylic acids or salts thereof have a documented, long history of use as corrosion inhibitors in liquid and solid media. They can function as corrosion inhibitors for metals in contact with water or aqueous solutions. They can serve as corrosion inhibitors in aqueous solutions that have low to high salt concentrations, wherein those salts include, but are not limited to alkali or alkaline metal salts of halides or other anionic components. They can function as corrosion inhibitors in the absence or presence of added substances. When they function as corrosion inhibitors in the presence of added substances the added substances may provide a positive synergistic corrosion inhibitory effect. Hydroxycarboxylic acids or salts forms with a single carboxylic acid function or multiple carboxylic acid functions can perform as corrosion inhibitors. Salt forms of these hydroxycarboxylic acids as corrosion inhibitors may have different cation components such as, but not limited to, alkali and alkaline earth cations. Hydroxycarboxylic acids or salt forms can serve as corrosion inhibitors against a number of metals, including, but not limited to iron, aluminum, copper and zinc. The hydroxycarboxylic acids or salt forms can serve as corrosion inhibitors in a multitude of applications where the use of nontoxic agents is an important advantage or requirement in the application, including but not limited to: cleaning of metal equipment; as corrosion inhibiting agents with corrosive salts, or other materials; for deicing purposes on surfaces in cold weather; in applications involving storage or transport of water or aqueous solutions in metal containers or conduits; in concrete and concrete containing metal components such as structural steel bars.
A need however remains for the availability of environmentally desirable materials for use as corrosion inhibiting agents for a variety of applications. Furthermore, it is clear that there is a need for such materials on a commercial scale for applications that include, but are not limited to, corrosion inhibiting agent in use with deicing agents for use on roadways and pedestrian walkways affected by snow and ice during cold weather periods, for use in concrete in contact with metal reinforcing bars, for cleaning boilers and other metal equipment. Materials that employ good corrosion inhibiting characteristics, are environmentally desirable, and can be produced economically on a large scale would be welcomed for commercial application on a large scale.
Hydroxycarboxylic acids and hydroxycarboxylic salts are also widely described as admixtures to concrete used to favorably influence different characteristics of concrete. Hydroxycarboxylic acids as admixtures (additives) to concrete formulations can serve to favorably effect how the concrete is applied and provide favorable characteristics of the concrete once it has hardened and is in use. Concrete admixtures include but are limited to roles as high-performance water reducers, improve concrete strength, and improve slump contraction (Wang, 2007). Such materials have been employed as set retarding additives (U.S. Published Patent Application No. US 2005-271431), as a set retarder for downhole use (Drochon, 2003), as components to aid in production of rapid setting cement (U.S. Published Patent Application No. 2002-228008), as components of aqueous cementing fluids to increase compression strength (U.S. Published Patent Application No. 2; 004-822459), as a setting controlling agent (e.g. tartaric acid, K Na tartrate, and trisodium citrate) for use in production of cement hardened body (Sakamoto, 2004), as a component of a blowing material for repairing degraded concrete (Araki, 2003), as a component of a plasticizer or superplasticizer in cement (Cerulli, 2002), as a component of a water-proof agent for concrete (Wu, 1999), as components of low-shrinkage cements useful for paving (Sekiguchi, 1993), as components of lightweight cellular cement articles (Sakurada, 1989), as a component of a rust-preventing composition in cement for steel reinforcement (Nakano, 1986), as components of refractory cements for use at high temperatures (Denki, 1985), as a component of rapidly hardening cement (Denki II, 1985), as a component for retarding the setting of cement mortars for large deep wells (Ene, 1982). The polyhydroxycarboxylic acids used as components of the setting retardants described in Ene were prepared by oxidation of molasses with nitric acid at 90° C. followed by neutralization.
Consequently, it is clear that there is a need for polyhydroxycarboxylic acids and their salts on a commercial scale for concrete production applications as illustrated herein and include but are not limited to those uses, as they reflect only a portion of the reported uses in conjunction with concrete. Such materials are also environmentally desirable in concrete and in related mortar applications, and their large scale economic production would be welcomed for commercial application on a large scale.
Salts of glucaric acid are also sold as food supplements. Monopotassium glucarate (potassium hydrogen glucarate) is used to maintain healthy cholesterol levels already within normal ranges, whereas calcium D-glucarate is used to promote glucuronidation, a process in which the body eliminates toxins and other adverse substances (U.S. Pat. Nos. 4,845,123; 5,561,160; and 5,364,644). Monopotassium glucarate has a relatively low water solubility (about 10%) and calcium D-glucarate is very insoluble in water. Therefore water soluble dipotassium D-glucarate hydrate (Styron, 2002) and monosodium monopotassium D-glucarate dihydrate (Styron, 2002) offer opportunities as food supplements and other applications where their water solubility is advantageous, and preferred over the less water soluble glucarate salts.
Given the long documented history of the effectiveness of hydroxycarboxylic acids as corrosion inhibitors and as components of cement and products therefrom, and their attraction as materials for safe use in the environment, it is desirable to have these materials available in large quantities for numerous applications. It is also desirable to be able to employ a single, basic technology to the oxidation of these varied polyols for the production of the desired hydroxycarboxylic acid salt products for use as corrosion inhibiting materials or concrete admixture materials. Furthermore, it is desirable to be able to apply the technology to a variety of polyol or carbohydrate feedstocks to produce oxidation products with attractive properties that extend beyond those cited here. The currently employed commercial methods of preparation of the common hydroxycarboxylic acids or salts thereof are principally biologically induced transformations or fermentations, as for example in the production of tartaric acid (U.S. Pat. No. 2,314,831), gluconic acid (U.S. Pat. No. 5,017,485), and citric acid (U.S. Pat. No. 3,652,396). The fermentation of suitable carbohydrate feedstocks for fermentation to the target acid requires specific microorganisms and special conditions to effect each of the fermentations, which are complex and multistep processes (Wisconsin Biorefiners).
All patents, patent applications, provisional patent applications and publications referred to or cited herein, are incorporated by reference in their entirety to the extent they are not inconsistent with the teachings of the specification.